High-water material coal gangue filling body bearing performance optimization numerical simulation method

Abstract

The invention discloses a high-water material coal gangue filling body bearing performance optimization numerical simulation method, which comprises the following steps: firstly, obtaining a stress-strain curve and a failure form of a high-water material test piece through a loading test, then establishing a high-water material test piece numerical model, and obtaining corresponding parameters through simulation loading, thereby establishing a required numerical model; then measuring the viscosity parameter of the high-water material slurry, and calculating the volume of the coal gangue particles entering the slurry and the motion characteristics of the coal gangue particles in the slurry; subsequently, obtaining a coal gangue particle distribution model by obtaining coal gangue distribution conditions of coal gangue particles in slurry with different viscosities; the distribution model and the numerical model are fused, so that a numerical model of the high-water filling body containing the coal gangue is established; the model is used for testing the mechanical property of the filling body, the influence rule of coal gangue particle parameters and distribution forms on the mechanical property of the filling body is analyzed, and on the basis, the coal gangue particle distribution forms under different coal gangue and slurry parameters are pre-presented, and the bearing performance of the filling body is predicted.

Description

Technical Field

[0001] The invention relates to a numerical simulation method for optimizing the bearing performance of a high-water material coal gangue filling body, and belongs to the technical field of filling body mechanics testing. Background Art

[0002] The goaf-retaining technology that uses high-water-density material filling to replace coal pillars can achieve the secondary utilization of tunnels and the recovery of coal pillar resources. It is a new type of green mining technology. Coal gangue is solid waste generated during coal mining and washing. It is usually stored on the surface, occupying land resources and posing hidden dangers such as fire, landslide and collapse. Crushing the coal gangue into particles and placing it in the high-water-density material filling as aggregate particles can not only reduce waste accumulation, but also reduce the use of high-water-density materials and further improve the environmental protection of goaf-retaining technology. It takes a certain amount of time from the high-water-density material being placed in the water and stirred to condensing into a solid. During this process, the migration characteristics of coal gangue particles in the slurry are difficult to monitor. Affected by the solid-liquid density, the coal gangue particles are unevenly distributed, floating or sinking to the bottom. The influence of these different coal gangue distribution forms on the strength of the filling body is currently unknown.

[0003] If the test method of laboratory casting specimens is used to solve the above problems and optimize the ratio of coal gangue high-water filling body and the proportion of material components to improve the bearing capacity of the filling body, a large number of experiments will be required, and it will be impossible to control the consistency of parameters such as the distribution morphology of coal gangue in each experiment. This will lead to non-unique experimental variables, which will in turn affect the accuracy of the experimental results.

[0004] In summary, how to provide a new method that can visualize the distribution morphology of coal gangue particles in slurry and analyze the influence of coal gangue particle parameters and distribution morphology on the mechanical properties of the filling body, and on this basis predict the distribution morphology of coal gangue particles under different coal gangue and slurry parameters and predict the bearing capacity of the filling body, and the whole process does not require repeated experiments, is the research direction required by the present invention. Summary of the invention

[0005] In view of the problems existing in the above-mentioned prior art, the present invention provides a numerical simulation method for optimizing the bearing performance of high-water material coal gangue filling bodies, which can visualize the distribution morphology of coal gangue particles in the slurry and analyze the influence of coal gangue particle parameters and distribution morphology on the mechanical properties of the filling body, and on this basis, predict the distribution morphology of coal gangue particles under different coal gangue and slurry parameters and predict the bearing performance of the filling body, and the whole process does not require repeated experiments.

[0006] In order to achieve the above purpose, the technical solution adopted by the present invention is: a numerical simulation method for optimizing the bearing performance of high-water material coal gangue filling body, the specific steps are:

[0007] A. Testing mechanical properties and modeling: Cast several cylindrical high-water material specimens of set sizes according to the designed water-cement ratio and cure for 7 days; Take samples from the gangue-producing rock layer and process them into cylindrical gangue specimens, and the size of the specimens is the same as that of the high-water material specimens; Use a servo press to pressurize the specimens at a constant speed or constant displacement until the specimens are destroyed, and obtain the stress-strain curve and failure morphology of each specimen during the loading process; Use PFC3D to establish a numerical model of high-water material specimens of set sizes, use the Linear Parallel Bond contact model to bond, attach parameters to the contact model and use the same loading parameters as the servo press to correct the contact parameters, continue to simulate the loading process until the stress-strain curve and failure morphology of the numerical model are consistent with the data and failure morphology of the actual loaded specimen, determine the current parameters as the corresponding parameters of the numerical model, and complete the numerical model establishment process;

[0008] B. Determine the viscosity parameters of the high-water-content material slurry: Use a rotational viscometer method or a dynamic shear rheometer method to test the viscosity of the high-water-content material slurry at different times during the solidification process. After the slurry is completely solidified, fit the data to obtain the viscosity-time function curve f(t) of the high-water-content material slurry;

[0009] C. Calculate the volume and movement characteristics of gangue particles entering water: Determine the volume proportion and particle size distribution of gangue particles in the high-water material specimen containing gangue particles. In the numerical model, spheres with the same diameter as the gangue particles are used to replace them. The number of spheres is n, where n is the volume of the cylinder in the numerical model × volume proportion / particle volume; and obtain the movement characteristics of the spheres after entering the high-water material slurry through simulation;

[0010] D. Extract particle position and geometric model: When the density of coal gangue is greater than the density of high-water material slurry, traverse each sphere velocity through fish language. When the velocity of a sphere increases from a negative number (i.e. sinking) to greater than 0 (i.e. floating), clear the sphere velocity and keep it at 0. After the numerical model runs in equilibrium, derive the coal gangue particle distribution model.

[0011] E. Establishing a specimen model: importing the gangue particle distribution model obtained in step D into the numerical model established in step A, and naming each sphere and contact corresponding to the gangue particle distribution model in the geometric space of the numerical model as gangue particles, and the remaining spheres and contacts as high-water material particles; then assigning the calibrated contact parameters of the gangue specimen and the high-water material specimen obtained in step A to the gangue contact parameters and the high-water material contact parameters, respectively, to complete the establishment of a numerical model of a high-water filling body containing gangue;

[0012] F. Test the mechanical properties and analyze the influence of distribution morphology: Use the numerical model obtained in step E to first set the volume ratio of high-water material to gangue particles to m:1, the height of gangue from the slurry surface to h, and the radius of gangue particles to r, substitute the measured viscosity function f(t), and use the same loading parameters as the servo press to perform a simulated loading test, so as to obtain the bearing capacity and apparent failure characteristics of the high-water filling body containing gangue under this condition; use the control variable method to adjust one of the volume ratio of high-water material to gangue particles, viscosity function, height and gangue particle radius, and keep other data unchanged, and repeat the simulated loading test, so as to obtain the influence of a certain variable on the strength of the filling body, and determine the high-water material water-cement ratio, viscosity function, height and gangue particle radius corresponding to the optimal bearing capacity of the filling body according to the simulation results, so as to optimize the bearing capacity of the actual filling body according to the obtained data.

[0013] Further, the cylindrical high water material specimen with the size set in step A is Cylindrical high water material specimen.

[0014] Furthermore, in step C, the movement characteristics of the gangue particles after entering the high-water material slurry are simulated, specifically:

[0015] The sphere is initially generated above the numerical model and its speed is fixed to 0. h is the distance from the grouting port to the slurry surface. The speed V(t) of each sphere in the z direction is monitored by software commands, and the high-water material slurry is controlled by fish language to apply resistance to each sphere. The resistance calculation formula is as follows:

[0016] F resistance = F floating + F sticking (1)

[0017]

[0018] F sticky = 6πf(t)rV(t)(3)

[0019] Where: 液 is the slurry density, kg / m 3 ; r is the radius of the sphere, m; g is the acceleration due to gravity, m / s 2 ;h 上 -The height of the sphere floating on the slurry above the liquid surface, m;

[0020] The buoyancy of the sphere simulating the particles after entering the liquid is calculated using the above formula, and the buoyancy is applied to the z direction of the sphere. Since the sphere is not affected by external forces in the x and y directions in the liquid, it is considered to be in free motion, thereby reproducing the movement characteristics of the sphere after entering the high-water material slurry.

[0021] Furthermore, the time interval between each measurement in step B is 0.5h.

[0022] Furthermore, the adjustment of the viscosity function in step F is achieved by reducing the water-cement ratio of the high-water material or adding other materials that are beneficial to increasing the viscosity; the adjustment of the height is achieved by adjusting the distance between the slurry outlet and the slurry surface.

[0023] Compared with the prior art, the present invention firstly makes high-water-content material specimens and coal gangue specimens of set sizes, and obtains the stress-strain curve and failure morphology of each specimen through loading test, then uses PFC3D to establish a numerical model of the high-water-content material specimen and obtains the corresponding parameters through simulating the loading process, thereby establishing the required numerical model; then determines the viscosity parameters of the high-water-content material slurry, and calculates the volume of coal gangue particles entering the slurry and the movement characteristics in the slurry; subsequently, obtains the distribution of coal gangue particles in slurries of different viscosities, and obtains A gangue particle distribution model is obtained; the distribution model is integrated with the numerical model to establish a numerical model of a high-water filling body containing gangue; the model is used to test its mechanical properties and analyze the influence of the distribution morphology of gangue particles; from the above, it can be seen that the present invention can visualize the distribution morphology of gangue particles in the slurry and analyze the influence of the parameters and distribution morphology of gangue particles on the mechanical properties of the filling body, and on this basis, the distribution morphology of gangue particles under different gangue and slurry parameters is predicted and the bearing capacity of the filling body is predicted, and the whole process does not need to be repeated many times. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 It is a schematic diagram of the numerical model of the high water material specimen established by the present invention;

[0025] Figure 2 It is a viscosity-time function curve of the high water material slurry in the present invention;

[0026] Figure 3 It is a distribution morphology diagram of coal gangue in slurries of different viscosities in the present invention;

[0027] Figure 4 It is a test piece model after slurries with different viscosities are combined with coal gangue in the present invention. DETAILED DESCRIPTION

[0028] The present invention will be further described below.

[0029] As shown in the figure, the specific steps of the present invention are:

[0030] A. Test mechanical properties and modeling: Cast according to the designed water-cement ratio to form several The cylindrical high-water-density material specimens were prepared and cured for 7 days; samples were taken from the gangue-producing rock layer and processed into cylindrical gangue specimens, and the size of the specimens was the same as that of the high-water-density material specimens; a servo press was used to pressurize the specimens at a constant speed or constant displacement until the specimens were destroyed, and the stress-strain curves and failure forms of each specimen during the loading process were obtained; PFC3D was used to establish a numerical model of high-water-density material specimens of set size. Figure 1 As shown, the radius of the small sphere used to simulate the high-water material is no more than 1 mm, and the Linear Parallel Bond contact model is used for bonding. The contact model is attached with parameters and the contact parameters are corrected using the same loading parameters as the servo press. The simulated loading process is continued until the stress-strain curve and failure morphology of the numerical model are consistent with the data and failure morphology of the actual loaded specimen. The current parameters are determined as the corresponding parameters of the numerical model, and the numerical model establishment process is completed;

[0031] B. Determination of viscosity parameters of high water-content material slurry: Use rotational viscometer method or dynamic shear rheometer method to test the viscosity of high water-content material slurry at different times during the solidification process. The time interval between each measurement is 0.5h. After the slurry is completely solidified, the data is fitted to obtain the viscosity-time function curve f(t) of high water-content material slurry. Figure 2 As shown; the test equipment needs to be calibrated before the measurement, the temperature of the sample needs to be strictly controlled during the measurement and the test needs to be carried out in accordance with the standardized operating procedures;

[0032] C. Calculate the volume and movement characteristics of gangue particles entering water: Determine the volume proportion and particle size distribution of gangue particles in the high-water material specimen containing gangue particles. In the numerical model, spheres with the same diameter as the gangue particles are used instead. The number of spheres is n, and n is The numerical model of the cylinder volume × volume ratio / particle volume is obtained; and the movement characteristics of the sphere after entering the high-water material slurry with different viscosities are obtained through simulation, specifically:

[0033] The sphere is initially generated above the numerical model and its speed is fixed to 0. h is the distance from the grouting port to the slurry surface. The speed V(t) of each sphere in the z direction is monitored by software commands, and the high-water material slurry is controlled by fish language to apply resistance to each sphere. The resistance calculation formula is as follows:

[0034] F resistance = F floating + F sticking (1)

[0035]

[0036] F sticky = 6πf(t)rV(t)(3)

[0037] Where: 液 is the slurry density, kg / m 3; r is the radius of the sphere, m; g is the acceleration due to gravity, m / s 2 ;h 上 -The height of the sphere floating on the slurry above the liquid surface, m;

[0038] The buoyancy of the sphere simulating the particles after entering the liquid is calculated using the above formula, and the buoyancy is applied to the z direction of the sphere. Since the sphere is not affected by external forces in the x and y directions in the liquid, it is considered to be in free motion, thereby reproducing the movement characteristics of the sphere after entering the high-water material slurry.

[0039] D. Extract particle position and geometric model: When the density of coal gangue is greater than the density of high-water material slurry, traverse each ball speed through the fish language. When the speed of a ball increases from a negative number (i.e. sinking) to greater than 0 (i.e. floating), clear the ball speed and keep it at 0; after the numerical model runs in equilibrium, export the coal gangue particle distribution model through the ball export geometry command; Figure 3 The figure shows the distribution morphology of coal gangue in slurries with different viscosities;

[0040] E. Establishing the specimen model: importing the gangue particle distribution model obtained in step D into the numerical model established in step A, and naming each sphere and contact corresponding to the gangue particle distribution model in the numerical model geometric space as gangue particles, and the remaining spheres and contacts as high-water material particles; then assigning the calibrated contact parameters of the gangue specimen and the high-water material specimen obtained in step A to the gangue contact parameters and the high-water material contact parameters, respectively, to complete the establishment of the numerical model of the high-water filling body containing gangue; Figure 4 The figure shows the specimen model after the slurries with different viscosities are combined with coal gangue;

[0041] F. Test the mechanical properties and analyze the influence of distribution morphology: Use the numerical model obtained in step E to first set the volume ratio of high-water material to gangue particles to m:1, the height of gangue from the slurry surface to h, and the radius of gangue particles to r, substitute the measured viscosity function f(t), and use the same loading parameters as the servo press to perform a simulated loading test, so as to obtain the bearing capacity and apparent failure characteristics of the high-water filling body containing gangue under this condition; use the control variable method to adjust one of the volume ratio of high-water material to gangue particles, viscosity function, height and gangue particle radius, and keep other data unchanged, and repeat the simulated loading test, so as to obtain the influence of a certain variable on the strength of the filling body, and determine the high-water material water-cement ratio, viscosity function, height and gangue particle radius corresponding to the optimal bearing capacity of the filling body according to the simulation results, so as to optimize the bearing capacity of the actual filling body according to the obtained data.

[0042] The adjustment of the above viscosity function is achieved by reducing the water-cement ratio of high-water materials or adding other materials that are beneficial to increasing viscosity; the adjustment of height is achieved by adjusting the distance between the slurry outlet and the slurry surface.

[0043] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principle of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. A numerical simulation method for optimizing the bearing performance of high-water-density coal gangue filling, characterized in that: The specific steps are: A. Testing mechanical properties and modeling: Cast several cylindrical high-water material specimens of set size according to the designed water-cement ratio and cure for 7 days; Take samples from the gangue-producing rock layer and process them into cylindrical gangue specimens, and the size of the specimens is the same as that of the high-water material specimens; Use a servo press to pressurize the specimens at a constant speed or constant displacement until the specimens are destroyed, and obtain the stress-strain curve and failure morphology of each specimen during the loading process; PFC3D is used to establish a numerical model of a high-water-density material specimen of a set size, and the Linear Parallel Bond contact model is used for bonding. The contact model is attached with parameters and the contact parameters are corrected using the same loading parameters as the servo press. The simulated loading process is continued until the stress-strain curve and failure morphology of the numerical model are consistent with the data and failure morphology of the actual loaded specimen. The current parameters are determined as the corresponding parameters of the numerical model to complete the numerical model establishment process. B. Determine the viscosity parameters of the high-water-content material slurry: Use a rotational viscometer method or a dynamic shear rheometer method to test the viscosity of the high-water-content material slurry at different times during the solidification process. After the slurry is completely solidified, fit the data to obtain the viscosity-time function curve f(t) of the high-water-content material slurry; C. Calculate the volume and movement characteristics of gangue particles entering water: Determine the volume proportion and particle size distribution of gangue particles in the high-water material specimen containing gangue particles. In the numerical model, spheres with the same diameter as the gangue particles are used to replace them. The number of spheres is n, where n is the volume of the cylinder in the numerical model × volume proportion / particle volume; and obtain the movement characteristics of the spheres after entering the high-water material slurry through simulation; D. Extract particle position and geometric model: Under the condition that the density of coal gangue is greater than the density of high-water material slurry, traverse each sphere speed through fish language. When the speed of a sphere increases from a negative number to greater than 0, clear the sphere speed to keep it at 0; after the numerical model runs in equilibrium, derive the coal gangue particle distribution model; E. Establishing a specimen model: importing the gangue particle distribution model obtained in step D into the numerical model established in step A, and naming each sphere and contact corresponding to the gangue particle distribution model in the geometric space of the numerical model as gangue particles, and the remaining spheres and contacts as high-water material particles; then assigning the calibrated contact parameters of the gangue specimen and the high-water material specimen obtained in step A to the gangue contact parameters and the high-water material contact parameters, respectively, to complete the establishment of a numerical model of a high-water filling body containing gangue; F. Test the mechanical properties and analyze the influence of distribution morphology: Use the numerical model obtained in step E to first set the volume ratio of high-water material to coal gangue particles to m:1, the height of coal gangue from the slurry surface to h, and the radius of coal gangue particles to r, bring in the measured viscosity function f(t), and use the same loading parameters as the servo press to perform a simulated loading test, so as to obtain the bearing capacity and apparent failure characteristics of the high-water filling body containing coal gangue under this condition; The control variable method is adopted to adjust one of the volume ratio of high-water material to gangue particles, viscosity function, height and radius of gangue particles, and keep other data unchanged. The simulated loading test is repeated to obtain the influence of a certain variable on the strength of the filling body. The water-cement ratio of the high-water material, viscosity function, height and radius of gangue particles corresponding to the optimal bearing performance of the filling body are determined according to the simulation results, so as to optimize the bearing performance of the actual filling body according to the obtained data.

2. According to claim 1, the numerical simulation method for optimizing the bearing performance of high-water material gangue filling body is characterized in that: The cylindrical high-water material specimen with the size set in step A is Cylindrical high water material specimen.

3. The numerical simulation method for optimizing the bearing performance of high-water-density coal gangue filling body according to claim 1 is characterized in that: In step C, the movement characteristics of the gangue particles after entering the high-water material slurry are simulated, specifically: The sphere is initially generated above the numerical model and its speed is fixed to 0. h is the distance from the grouting port to the slurry surface. The speed V(t) of each sphere in the z direction is monitored by software commands, and the high-water material slurry is controlled by fish language to apply resistance to each sphere. The resistance calculation formula is as follows: F resistance = F floating + F sticking (1) F sticky = 6πf(t)rV(t)(3) Where: 液 is the slurry density, kg / m 3 ; r is the radius of the sphere, m; g is the acceleration due to gravity, m / s 2 ;h 上 -The height of the sphere floating on the slurry above the liquid surface, m; The above formula can reproduce the movement characteristics of the sphere after entering the high-water material slurry.

4. The method for optimizing the bearing performance of high-water-density coal gangue filling according to claim 1 is characterized in that: The time interval between each measurement in step B is 0.5 h.

5. The method for optimizing the bearing performance of high-water-density coal gangue filling according to claim 1 is characterized in that: The adjustment of the viscosity function in step F is achieved by reducing the water-cement ratio of the high-water material or adding other materials that are beneficial to increasing the viscosity; the adjustment of the height is achieved by adjusting the distance between the slurry outlet and the slurry surface.

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